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gpio: core: fix const-correctness of gpio_chip_guard

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The DEFINE_CLASS macro for gpio_chip_guard currently expects a non-const
struct gpio_desc pointer. This prevents the guard from being used cleanly
in fast paths that receive a const descriptor, forcing developers to fall
back to open-coding the SRCU locks.

Update the macro to accept a const struct gpio_desc pointer. This is valid
because the actual targeted gpio_device pointer assignment does not drop
const qualifiers on the target structure.

Convert the open-coded SRCU locks in gpiod_get_raw_value_commit() and
gpiod_to_irq() to use the guard, removing their legacy FIXME comments.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Marco Scardovi <scardracs@disroot.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260524162708.62949-2-scardracs@disroot.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This commit is contained in:
Marco Scardovi (scardracs) 2026-05-24 18:27:07 +02:00 committed by Bartosz Golaszewski
parent 9de94681ee
commit aa7e8b7ef0
2 changed files with 9 additions and 21 deletions
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28
drivers/gpio/gpiolib.c
View File

@ -3428,20 +3428,13 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des
static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
{
struct gpio_device *gdev;
struct gpio_chip *gc;
int value;
/* FIXME Unable to use gpio_chip_guard due to const desc. */
gdev = desc->gdev;
guard(srcu)(&gdev->srcu);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc)
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
value = gpio_chip_get_value(gc, desc);
value = gpio_chip_get_value(guard.gc, desc);
value = value < 0 ? value : !!value;
trace_gpio_value(desc_to_gpio(desc), 1, value);
return value;
@ -4148,8 +4141,6 @@ EXPORT_SYMBOL_GPL(gpiod_is_shared);
*/
int gpiod_to_irq(const struct gpio_desc *desc)
{
struct gpio_device *gdev;
struct gpio_chip *gc;
int offset;
int ret;
@ -4157,16 +4148,13 @@ int gpiod_to_irq(const struct gpio_desc *desc)
if (ret <= 0)
return -EINVAL;
gdev = desc->gdev;
/* FIXME Cannot use gpio_chip_guard due to const desc. */
guard(srcu)(&gdev->srcu);
gc = srcu_dereference(gdev->chip, &gdev->srcu);
if (!gc)
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
offset = gpiod_hwgpio(desc);
if (gc->to_irq) {
ret = gc->to_irq(gc, offset);
if (guard.gc->to_irq) {
ret = guard.gc->to_irq(guard.gc, offset);
if (ret)
return ret;
@ -4174,7 +4162,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
return -ENXIO;
}
#ifdef CONFIG_GPIOLIB_IRQCHIP
if (gc->irq.chip) {
if (guard.gc->irq.chip) {
/*
* Avoid race condition with other code, which tries to lookup
* an IRQ before the irqchip has been properly registered,

2
drivers/gpio/gpiolib.h
View File

@ -244,7 +244,7 @@ DEFINE_CLASS(gpio_chip_guard,
_guard;
}),
struct gpio_desc *desc)
const struct gpio_desc *desc)
int gpiod_request(struct gpio_desc *desc, const char *label);
int gpiod_request_commit(struct gpio_desc *desc, const char *label);